Ultra-low-noise tunnel junction dc SQUID
The design, fabrication, and noise properties of an ultra-low-noise tunnel junction dc SQUID (superconducting quantum interference device) are presented. The two resistively shunted Pb-alloy tunnel junctions are each 3.6 ..mu..m diam. The SQUID has an inductance L of approx. =11 pH, a critical current per junction, I/sub 0/ of approx. =100 ..mu..A, and a resistance per shunt R of approx. =2 ..cap omega... At 2.3 K, eI/sub 0/Rapprox. =k/sub B/T, and simple theory predicts that the minimum intrinsic energy sensitivity should be approx. =2h. The actual minimum value of the measured high-frequency (70 kHz) flux noise at 4.2 K is phi/sub n/=1.3 x 10/sup -7/phi/sub 0/ Hz/sup -1/2/. This corresponds to an intrinsic energy sensitivity, phi/sup 2//sub n//2L, of 3.2 x 10/sup -33/ J Hz/sup -1/ or 5h. Lowering the bath temperature to 1.8 K gave no improvement in performance.
- Research Organization:
- IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598
- OSTI ID:
- 5776639
- Journal Information:
- Appl. Phys. Lett.; (United States), Journal Name: Appl. Phys. Lett.; (United States) Vol. 35:10; ISSN APPLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALLOYS
COMPARATIVE EVALUATIONS
CRITICAL CURRENT
CURRENTS
DATA
DESIGN
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELECTRONIC EQUIPMENT
ENERGY DEPENDENCE
FABRICATION
FLUXMETERS
INFORMATION
JUNCTIONS
LEAD ALLOYS
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
NOISE
PHYSICAL PROPERTIES
SENSITIVITY
SQUID DEVICES
SUPERCONDUCTING DEVICES
TEMPERATURE DEPENDENCE
TUNNEL EFFECT
ULTRALOW TEMPERATURE